An intercooler that cools supercharged intake air is known, which performs heat exchange between the supercharged air supplied to an engine by a supercharger and two types of cooling water having temperatures different from each other (see, for example, Patent Literature 1). In the intercooler disclosed in Patent Document 1, the hot cooling water makes a U-turn on the upstream side in the flow direction of the supercharged intake air, and the cold cooling water makes a U-turn on the downstream side in the flow direction of the supercharged intake air. In the hot cooling water flow path and the cold cooling water flow path, inner fins for promoting heat exchange between the cooling water and the supercharged intake air are provided.
According to the configuration as above, the cold cooling water can be warmed quickly with heat of the hot cooling water at engine start-up. Further, because the supercharged intake air can be pre-cooled with the hot cooling water before the supercharged intake air is cooled with the cold cooling water, cooling performance of a supercharged intake air cooling system can be improved.